Metal coated particles



March 17, 1964 J. A. H. LUND ETAL 3,124,838

APPARATUS FOR COMPACTING METAL AND METAL COATED PARTICLES Filed Sept. 14, 1961 452 FIG.- 2

Inventors J. A. H. LUND b T/BOR KRANTZ {Marne y United States Patent 3,124,838 APPARATUS FOR COMPACTING METAL METAL COATED PARTICLES John A. H. Lund, Vancouver, British Columbia, and Tihor Krantz, Fort Saskatchewan, Alberta, Canada, assignors to Sherritt Gordon Mines Limited, Toronto, Ontario, Canada, a company of Qntari'o Filed Sept. 14, 1961, Ser. No. 138,116 2 Claims. ((11. 18-9) This invention relates to improvements in a roll compacting unit of the type employed for roll compacting metal powder into rods, sheets, strips, wire and the like. It is particularly directed to providing improved means for confining metal powder to the roll gap and for facilitating the discharge of compacted product from the unit.

Metal powder is compacted initially into a green shape, such as in the form of sheet or strip, by feeding it, usually at a predetermined, uniform rate, into the roll gap of a pair of oppositely positioned, horizontally disposed, pressure rolls. The rolls are spaced to produce a self-supporting, partially densified green shape of desired thickness.

There are problems in roll compacting metal powder by this method. The metal powder tends to flow or leak from the ends of the rolls during compaction with the result that the longitudinal edges of the sheet or strip are not compacted to the same degrees of density, coherence and thickness as is the central portion. Thus, it has been necessary to trim the longitudinal edges of the strip or sheet which results in the production of an appreciable percentage of waste material in addition to non-uniformity in the mechanical characteristics of the product across its width.

Devices have been designed to confine the metal powder between the ends of the rolls during the roll compacting operation. One known type of metal powder confining device includes a flexible disc mounted on the roll shaft at each end of one of the rolls. The discs are of greater diameter than the roll on which they are mounted by at least the width of the roll gap. The discs are pressed against the opposing faces of the ends of the roll at the roll gap and thus confine the metal powder within the roll gap and the leakage of metal powder from the ends of the roll is prevented. In one known type of disc, they are pressed against the opposing faces of the ends of the rolls at the roll gap to confine the metal particles to the roll gap and away from the opposing faces of the ends of the roll at a point beyond the roll gap thus to permit the green strip or sheet to discharge from the roll gap without friction or binding.

A further known arrangement for confining metal powder to the roll gap involves two rigid, circular discs or flanges of a diameter greater than the rolls by at least the width of the roll gap. A disc is mounted on the roll shaft at one end of one roll and a second disc is mounted on the roll shaft at the other end of the other roll. These discs are of a rigid type and are fitted tightly against the opposing faces of the ends of the rolls.

The known arrangements are satsifactory insofar as confining the metal powder to the roll gap but it is found that in use they create a further problem. The discs or flanges are of a diameter greater than that of the roll on which they are mounted. Consequently, a disc mounted on the end of one roll overlaps the opposing end of the opposite roll. It is found in the operation of the roll compacting unit that the rolls tend to move relative to each other in the direction of their axes of rotation. This movement may only be very slight, of the order of, for example, from one to ten one-thousandths of an inch. However, it is sufiicient for the discs to bind against the opposing faces of the ends of the rolls and wear grooves in the opposing faces of the discs. These grooves at least form defects in the longitudinal edges of the strip or sheet and may interfere with the smooth and unimpeded discharge from the roll gap.

We have found that difliculties which result from movement along the axis of rotation of each roll in a direction opposite to the movement of the other roll can be overcome by first determining the direction of the relative movement of the rolls along their axes of rotation. A flexible disc or flange is then mounted on the roll shaft at that end of one of the rolls which normally tends to move away from the opposing end of the other roll during the operation of the roll compacting unit. A second flexible disc or flange is mounted on the roll shaft at the opposite end of the other roll. As the movements of the rolls are in opposite directions, that disc also moves away from the opposing end of the opposite roll during operation of the unit. Means are provided to press the discs against the opposing faces of the ends of the rolls from a point adjacent to the inlet end of the roll gap, to prevent the leakage of metal powder from the ends of the roll gap and into the space or joint between the ends of the rolls and discs and to restrain the discs against deflection at the point of maximum deflection, to a point beyond the roll gap. Means also are provided spaced from the roll gap to press the discs away from the opposing ends of the rolls, thus to permit the free and unimpeded discharge of the partially compacted sheet or strip from the roll gap.

An understanding of the improved roll compacting uni of this invention can be obtained from the following description, reference being made to the accompanying drawing, in which:

FIGURE 1 is a perspective view of a metal powder roll compacting unit comprising a pair of oppositely positioned, horizontally disposed rolls which incorporate the metal powder confining discs or flanges of this invention;

FIGURE 2 is a top plan view; and

FIGURE 3 is an end view.

Like reference characters refer to like parts throughout the description and drawing.

As used herein, the term metal particles is intended to include, but is not necessarily limited to, particles of metal, metal alloy, composite metal coated metal and non-metal particles and compounds such as are produced by spraying, mechanical attrition and precipitation from solutions by chemical reaction.

Referring to the drawing, the numerals 20-21 indicate rotatable rolls of a conventional type used for compacting metal particles. In the modification illustrated, they are plain, or unprofiled, hard, ground steel rolls adapted to compact metal particles into sheet or strip. The rolls are mounted on shafts 2223, respectively, which are driven according to conventional practice, such as by an electric motor through a train of reducing gears. The rolls are formed of conventional material, such as steel, and, conventionally, are adjustably mounted in exactly opposing relationship in a horizontal plane to apply a pressure on the particulate material fed into the roll gap or space 24. conventionally, provision is made to increase or reduce the width of the roll gap, thus to increase or reduce the thickness of the resulting sheet or strip, and to increase or reduce the pressure applied to the sheet or strip thus to increase or reduce its green strength, coherency and density. Using smooth, hard, ground steel rolls six inches in diameter, self-supporting nickel strip of from 0.02 to 0.04 inch thick and of a density of about of the theoretical was produced from nickel powder of a particle size within the range of from about 1 to about microns with pressures estimated at up to about 75 tons per square inch.

Methods and apparatus are known and are in use for feeding metal powder to the roll gap at a relatively uniform rate and do not form part of this invention.

The numerals 30-31 indicate flexible discs or flanges of a radius greater than that of the rolls with which they are associated by at least the amount of the roll gap. Disc 30 is mounted on roll shaft 22 at one end of roll and disc 31 is mounted on roll shaft 23 at the other end of roll 21. The discs are secured to the roll shafts for rotation therewith according to conventional practice, such as by keys or set screws, not shown. As indicated by the directions of the arrows, FIGURES 1 and 2, which indicate the displacement of the rolls in use in the direction of their axes of rotation, the disc is mounted at the end of roll 20 which moves away from the opposing end of roll 21 and the disc 31 is mounted at the end of the roll 21 which moves away from the opposing end of roll 20. Thus, each roll is free to move in opposite directions along its axis of rotation without binding of the discs against the opposing ends of the rolls.

The discs or flanges 3031 are formed of material such as steel, of sufiicient strength to withstand the lateral forces of the metal powder during compacting but are sufiiciently flexible so that they can be pressed tightly against the opposing faces of the ends of the rolls from a point approaching the roll gap to a point beyond the roll gap and to be flexed or pressed away from the opposing ends of the rolls at a point spaced from the roll gap so that the product is discharged smoothly from the roll compacting unit without binding between the discs.

A suitable arrangement for flexing the discs at the desired points includes a train of rollers 4tla which are mounted to press the disc with which they are associated against the opposing faces of the rolls as the disc approaches the roll gap in its rotation. The train includes a roller, or pin, 4141a, positioned at the roll gap to retain the disc firmly against the opposing face of the roll and thus resist the tendency of the disc to flex at the point at which the maximum lateral pressure of the metal particles is applied against it.

The discs are flexed, or spread, away from the opposing faces of the ends of the rolls at a point spaced from the roll gap by rollers or pins 45-4511 which bear against the inside faces of the discs. Preferably, as illustrated in the drawing, the pins or rollers 4141a and 4545a are spaced about apart.

The improved roll compacting unit of this invention possesses several important advantages. Metal particles being compacted are confined to the roll gap and leakage from the roll gap at the ends of the rolls is prevented. The discs are flexed or spread away from the compacted product and, accordingly, it is discharged from the rolls without impedance or binding. Also, the rolls are free to move in a horizontal plane in the direction of their axes of rotation without binding or wear on the opposing faces of the discs.

What we claim as new and desire to protect by Letters Patent of the United States is:

1. A rolling mill for producing compacted shapes from metal and metal coated particles which comprises a pair of rotatable, oppositely positioned rolls mounted on horizontal roll shafts in spaced relation and defining a roll-gap therebetween, said rolls having a normal tendency to shift axially in opposite directions when rotated under load, means for confining particles to the roll gap which comprises two flexible discs of a radius greater than the radius of the rolls by at least the width of the roll gap, one of said flexible discs being mounted on one of the rolls at the end corresponding to the direction in which the roll would normally tend to shift axially and the other disc being mounted at the other end of the other roll whereby binding of the discs against the opposing faces of the rolls is avoided, means for pressing each disc firmly against the Opposing faces of the ends of the rolls during their rotation from a point approaching the roll gap to a point beyond the roll gap, and means for flexing the discs away from the opposing faces of the ends of the rolls at a point spaced from the roll gap.

2. A rolling mill for producing compacted shapes from metal and metal coated particles which comprises a pair of rotatable, oppositely positioned rolls mounted on hori- Zontal roll shafts in spaced relation and defining a roll-gap therebetween, said rolls having a normal tendency to shift axially in opposite directions when rotated under load, means for confining particles to the roll gap which comprises two flexible discs of a radius greater than the radius of the rolls by at least the width of the roll gap, one of said flexible discs being mounted on one of the rolls at the end corresponding to the direction in which the roll would normally tend to shift axially and the other disc being mounted at the other end of the other roll whereby binding of the discs against the opposing faces of the rolls is avoided, roller means for pressing each disc firmly against the opposing faces of the rolls during their rotation from a point approaching the roll gap to a point beyond the roll gap, and means for retaining said discs firmly in a vertical plane against the opposing faces of the ends of the rolls at said roll gap, and roller means for flexing the discs away from the opposing faces of the ends of the rolls at a point spaced from the roll gap.

References Cited in the file of this patent UNITED STATES PATENTS 2,904,829 Hech Sept. 22, 1959 3,017,665 Dasher et a1 Jan. 23, 1962 3,019,487 Naeser Feb. 6, 1962 

1. A ROLLING MILL FOR PRODUCING COMPACTED SHAPES FROM METAL AND METAL COATED PARTICLES WHICH COMPRISES A PAIR OF ROTATABLE, OPPOSITELY POSITIONED ROLLS MOUNTED ON HORIZONTAL ROLL SHAFTS IN SPACED RELATION AND DEFINING A ROLL-GAP THEREBETWEEN, SAID ROLLS HAVING A NORMAL TENDENCY TO SHIFT AXIALLY IN OPPOSITE DIRECTIONS WHEN ROTATED UNDER LOAD, MEANS FOR CONFINING PARTICLES TO THE ROLL GAP WHICH COMPRISES TWO FLEXIBLE DISCS OF A RADIUS GREATER THAN THE RADIUS OF THE ROLLS BY AT LEAST THE WIDTH OF THE ROLL GAP, ONE OF SAID FLEXIBLE DISCS BEING MOUNTED ON ONE OF THE ROLLS AT THE END CORRESPONDING TO THE DIRECTION IN WHICH THE ROLL WOULD NORMALLY TEND TO SHIFT AXIALLY AND THE OTHER DISC BEING MOUNTED AT THE OTHER END OF THE OTHER ROLL WHEREBY BINDING OF THE DISCS AGAINST THE OPPOSING FACES OF THE ROLLS IS AVOIDED, MEANS FOR PRESSING EACH DISC FIRMLY AGAINST THE OPPOSING FACES OF THE ENDS OF THE ROLLS DURING THEIR ROTATION FROM A POINT APPROACHING THE ROLL GAP TO A POINT BEYOND THE ROLL GAP, AND MEANS FOR FLEXING THE DISCS AWAY FROM THE OPPOSING FACES OF THE ENDS OF THE ROLLS AT A POINT SPACED FROM THE ROLL GAP. 